first of all this is what im using.
-RASPBERRY PI 2 MODEL B
-A 900MHz quad-core ARM Cortex-A7 CPU
now my problem, i was able to run doom and doom 2 on emulation station without any problems. but then for my own reasons i decided to delete emulation station(i formatted my micro sd card) i installed/burn image "RASPBIAN JESSIE" i use this for web browsing,minecraft pi and kodi and everything works fine, but then i decided to install dos box, i mounted/installed doom and doom 2, but for some reason the cpu cant handle the game, i can run it but everything is really slow, everything moves in slow motion.
why can i run this 2 games on emulation station without lag but not on Raspbian Jessie???????
....i don't get it, its the same hardware same roms same linux based programs yet i get different game performance...
what can i do other than get another micro sd card and install emulation station or download chocolate doom.